The work proposed will continue the study of factors protecting the stomach by digestion by its own secretions. The following lines of work will be followed: (1) The concentration and composition of proteins in gastric lymph will be studied under normal circumstances and when the gastric mucosa is damaged. (2) An attempt will be made to measure the rates of turnover of proteins in gastric lymph. (3) A study of protein-losing gastropathy produced by exposure to foreign proteins will be completed. (4) A study of protein-losing gastropathy produced by ethanol will be completed. (5) Light and electron microscopic observations of the gastric mucosa correlated with its functional state will be made.